//2009/08/21 18:23:38
#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <queue>
#include <sstream>
#include <algorithm>

using namespace std;

class ChessboardPattern
{
public:
    vector <string> makeChessboard(int rows, int columns)
    {
        vector<string> v;
        for (int i=0; i<rows; i++)
        {
            string result;
            for (int j=0; j<columns; j++)
                if ( ((rows-i+j) % 2) == 0)
                    result += "X";
                else
                    result += ".";
            v.push_back(result);
        }
        return v;
    }
};
